| 41. |
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| 42. |
- Ciosek, Katarzyna, et al.
(författare)
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Energy storage activities in the Swedish hybrid vehicle centre
- 2009
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Ingår i: World Electric Vehicle Journal. - : MDPI AG. - 2032-6653. ; 3:4, s. 858-862, s. 2850-2854
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Tidskriftsartikel (refereegranskat)abstract
- Significant efforts are put worldwide on developing new concepts for vehicle propulsion with the hybrid electric vehicle (HEV) being a prominent example. Hybrid technology is clearly a strategic future activity for automotive industries and in response to the rapid development in the area; the Swedish Hybrid Vehicle Centre (SHC) was formed in 2007 to join forces between Swedish industry and academia in the field. The centre emphasizes a holistic view to meet the environmental and societal needs with new technological solutions. The research within SHC is currently divided into three different themes whereof we here describe the Energy Storage theme with emphasis on the activities carried out at the involved universities in the current main project areas: Cell Properties, Electrode Materials and Electrolyte Additives. Examples are given on how these projects attacks the problems at hand separately, but also how we create synergy effects between the projects. As an example cell modelling is performed given a specific chemistry and cycling scheme, the same parameters are used for electrochemical experiments which provide macroscopic data that are connected with molecular level actions in the electrodes, the electrolyte, and the interfaces. All this is done using our base-line chemistry and a subsequent route is to investigate the role of different additives to overcome the limitations that are observed.
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| 43. |
- Clarke-Hannaford, Jonathan, et al.
(författare)
-
Spectroscopic and Computational Study of Boronium Ionic Liquids and Electrolytes
- 2021
-
Ingår i: Chemistry - A European Journal. - : Wiley. - 1521-3765 .- 0947-6539. ; 27:50, s. 12826-12834
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Tidskriftsartikel (refereegranskat)abstract
- Boronium cation-based ionic liquids (ILs) have demonstrated high thermal stability and a >5.8 V electrochemical stability window. Additionally, IL-based electrolytes containing the salt LiTFSI have shown stable cycling against the Li metal anode, the “Holy grail” of rechargeable lithium batteries. However, the basic spectroscopic characterisation needed for further development and effective application is missing for these promising ILs and electrolytes. In this work, attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy and density functional theory (DFT) calculations are used in combination to characterise four ILs and electrolytes based on the [NNBH2]+ and [(TMEDA)BH2]+ boronium cations and the [FSI]− and [TFSI]− anions. By using this combined experimental and computational approach, proper understanding of the role of different ion-ion interactions for the Li cation coordination environment in the electrolytes was achieved. Furthermore, the calculated vibrational frequencies assisted in the proper mode assignments for the ILs and in providing insights into the spectroscopic features expected at the interface created when they are adsorbed on a Li(001) surface. A reproducible synthesis procedure for [(TMEDA)BH2]+ is also reported. The fundamental findings presented in this work are beneficial for any future studies that utilise IL based electrolytes in next generation Li metal batteries.
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| 44. |
- Clarke-Hannaford, Jonathan, et al.
(författare)
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The (In-)Stability of the Ionic Liquids [(TMEDA)BH2][TFSI] and -[FSI] on the Li(001) Surface
- 2021
-
Ingår i: Batteries and Supercaps. - : Wiley. - 2566-6223. ; 4:7, s. 1126-1134
-
Tidskriftsartikel (refereegranskat)abstract
- Electrolytes that can enable the use of a Li metal anode at a vast 3860 mAh/g, in place of currently used graphite anodes (372 mAh/g), are required for the advancement of next-generation rechargeable Li batteries. Both quaternary ammonium and boronium (trimethylamine)(dimethylethylamine)dihydroborate [NNBH2](+) cation-based ionic liquids (ILs) show high electrochemical stability windows and thermal stability for use in Li batteries. Cyclization of the former cation shows improved electrolyte stability compared to the open-chain counterpart. However, it is not known whether this is the case for the cyclic derivative of [NNBH2](+), N,N,N',N'-tetramethylethylenediamine)dihydroborate [(TMEDA)BH2](+). Here, the details of the initial stages of solid-electrolyte interphase (SEI) layer formation on a lithium metal surface, Li(001), for the [(TMEDA)BH2](+) based ILs are revealed using density functional theory (DFT) calculations and ab initio molecular dynamics (AIMD) simulations. These indicate that [(TMEDA)BH2](+) remains intact, displaying a similarly weak interaction with the Li metal surface as the open-chain analogue. The chemical stability shown by the boronium cation indicates spontaneous and unwanted side reactions with the Li anode are unlikely to occur, which could help to facilitate long-term cycling stability of the battery. Altogether, the findings suggest the [(TMEDA)BH2](+) ILs, like their [NNBH2](+) IL counterparts, are viable candidates for rechargeable Li metal batteries.
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| 45. |
- Cznotka, E., et al.
(författare)
-
3D laser scanning confocal microscopy of siloxane-based comb and double-comb polymers in PVDF-HFP thin films
- 2016
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Ingår i: Journal of Coatings Technology Research. - : Springer Science and Business Media LLC. - 1935-3804 .- 1547-0091. ; 13:4, s. 577-587
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Tidskriftsartikel (refereegranskat)abstract
- Currently, atomic force microscopy is the preferred technique to determine roughness on membrane surfaces. In this paper, a new method to measure surface roughness is presented using a 3D laser scanning confocal microscope for high-resolution topographic analysis and is compared to conventional SEM. For this study, the surfaces of eight samples based on a poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) host polymer with different liquid interpenetrating components were analyzed. Polymethylhydrosiloxane, triethylene glycolallylmethyether, (3,3,3-trifluoropropyl) methylcyclotrisiloxane (D-3-C2H4CF3), polysiloxane-comb-propyloxymethoxytriglycol (PSx), poly-siloxane-comb-propyl-3,3,3-trifluoro (PSx-C2H4CF3), poly [bis(2-(2-methoxyethoxy) ethoxy) phosphazene, or poly [bis(trifluoro) ethoxy] phosphazene was chosen as interpenetrating compound to investigate the impact of comb and double-comb-structured polymer backbones, as well as their dipolar or fluorous residues on the PVDF-HFP-miscibility. Different phases of the constituting ingredients were identified via their thermal properties determined by DSC. Additionally, the COSMO-RS method supported the experimental results, and with regard to computed sigma-profiles, new modified structures for polysiloxane and polyphosphazene synthesis were suggested.
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| 46. |
- Das, S., et al.
(författare)
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Instability of Ionic Liquid-Based Electrolytes in Li-O2 Batteries
- 2015
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Ingår i: Journal of Physical Chemistry C. - : American Chemical Society (ACS). - 1932-7447 .- 1932-7455. ; 119:32, s. 18084-18090
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Tidskriftsartikel (refereegranskat)abstract
- Ionic liquids (ILs) have been proposed as promising solvents for Li-air battery electrolytes. Here, several ILs have been investigated using differential electrochemical mass spectrometry (DEMS) to investigate the electrochemical stability in a Li-O-2 system, by means of quantitative determination of the rechargeability (GER/ORR), and thereby the Coulombic efficiency of discharge and charge. None of the IL-based electrolytes are found to behave as needed for a functional Li-O-2 battery but perform better than commonly used organic solvents. Also the extent of rechargeability/reversibility has been found to be strongly dependent on the choice of IL cation and anion as well as various impurities.
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| 47. |
- Drvarič Talian, Sara, et al.
(författare)
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Fluorinated Ether Based Electrolyte for High-Energy Lithium-Sulfur Batteries: Li+ Solvation Role behind Reduced Polysulfide Solubility
- 2017
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Ingår i: Chemistry of Materials. - : American Chemical Society (ACS). - 1520-5002 .- 0897-4756. ; 29:23, s. 10037-10044
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Tidskriftsartikel (refereegranskat)abstract
- By employing new electrolytes, the polysulfide shuttle phenomenon, one of the main problems of lithium-sulfur (Li-S) batteries, can be significantly reduced. Here we present excellent Coulombic efficiencies as well as adequate performance of high-energy Li-S cells by the use of a fluorinated ether (TFEE) based electrolyte at low electrolyte loading. The observed altered discharge profile was investigated both by electrochemical experiments and an especially tailored COSMO-RS computational approach, while the details of the discharge mechanism were elucidated by two operando techniques: XANES and UV-vis spectroscopy. A significant decrease of polysulfide solubility compared to tetraglyme is due to different Li+ solvation mode.
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| 48. |
- Dussauze, M., et al.
(författare)
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Lithium Ion Conducting Boron-Oxynitride Amorphous Thin Films: Synthesis and Molecular Structure by Infrared Spectroscopy and Density Functional Theory Modeling
- 2013
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Ingår i: Journal of Physical Chemistry C. - : American Chemical Society (ACS). - 1932-7447 .- 1932-7455. ; 117:14, s. 7202-7213
-
Tidskriftsartikel (refereegranskat)abstract
- Li ion containing oxynitride amorphous thin films are promising materials for electrochemical applications due to their high ionic conductivity, mechanical stability and chemical durability. Here we report on the preparation of Li boron-oxynitride (LiBON) amorphous thin films by rf sputtering of Li-diborate and Li-pyroborate targets in nitrogen atmosphere. The materials produced were subsequently studied by infrared transmittance spectroscopy assisted by density functional theory calculations using representative Li boron-oxide and boron-oxynitride clusters. The combination of experiments and calculations allows us to propose accurate vibrational assignments and to clarify the complex infrared activity of the LiBON films. Both experimental and calculated spectra show that nitrogen incorporation induces significant structural rearrangements, manifested mainly by a change in boron coordination number from four to three, and by the formation of boron-nitrogen-boron bridges. The nature of boron-nitrogen bonding depends on the composition of the sputtering target, with an exponential relationship adequately describing the dependence of B-N stretching frequency on bond length. Besides bonding to two boron atoms by covalent bonds, the nitrogen atoms interact also with Li ions by participating in their coordination sphere together with oxygen atoms. Likely, boron-nitrogen bonding in LiBON films facilitates Li ion transport due to induced charge delocalization within the boron-nitrogen-boron bridges and reduced electrostatic interaction with the Li ions.
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| 49. |
- Edelbring, Samuel, PhD, Docent, 1969-, et al.
(författare)
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Should the PBL tutor be present? : A cross-sectional study of group effectiveness in synchronous and asynchronous settings
- 2020
-
Ingår i: BMC Medical Education. - : BioMed Central. - 1472-6920. ; 20:1
-
Tidskriftsartikel (refereegranskat)abstract
- Background: The tutorial group and its dynamics are a cornerstone of problem-based learning (PBL). The tutor's support varies according to the setting, and it is pertinent to explore group effectiveness in relation to different settings, for example online or campus-based. The PBL groups' effectiveness can partly be assessed in terms of cognitive and motivational aspects, using a self-report tool to measure PBL group effectiveness, the Tutorial Group Effectiveness Instrument (TGEI).This study's aim was to explore tutor participation in variations of online and campus-based tutorial groups in relation to group effectiveness. A secondary aim was to validate a tool for assessing tutorial group effectiveness in a Swedish context.Methods: A cross-sectional study was conducted with advanced-level nursing students studying to become specialised nurses or midwives at a Swedish university. The TGEI was used to measure motivational and cognitive aspects in addition to overall group effectiveness. The instrument's items were translated into Swedish and refined with an expert group and students. The responses were calculated descriptively and compared between groups using the Mann-Whitney U and Kruskal-Wallis tests. A psychometric evaluation was performed using the Mokken scale analysis. The subscale scores were compared between three different tutor settings: the tutor present face-to-face in the room, the tutor present online and the consultant tutor not present in the room and giving support asynchronously.Results: All the invited students (n=221) participated in the study. There were no differences in motivational or cognitive aspects between students with or without prior PBL experience, nor between men and women. Higher scores were identified on cognitive aspects (22.6, 24.6 and 21.3; p<0.001), motivational aspects (26.3, 27 and 24.5; p=002) and group effectiveness (4.1, 4.3, 3.8, p=0.02) for the two synchronously tutored groups compared to the asynchronously tutored group. The TGEI subscales showed adequate homogeneity.Conclusions: The tutor's presence is productive for PBL group effectiveness. However, the tutor need not be in the actual room but can provide support in online settings as long as the tutoring is synchronous.
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| 50. |
- Edstrom, K., et al.
(författare)
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The NordBatt Conferences: The Journey so Far and the Future Ahead
- 2023
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Ingår i: Batteries and Supercaps. - 2566-6223. ; 6:11
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- All great things have humble beginnings. In 2013 when NordBatt started, we had no lithium-ion battery manufacturing in the Nordic countries and we had rather few EVs on the roads, although things were clearly starting to move – Tesla Model S in fact topped the monthly new car sales of Norway in September that very year. Yet, even if the field was advancing and lively, relatively few Nordic research groups were doing any kind of battery R&D. Now, in 2023, almost everything is different; batteries and “electrify everything” are seen, not only by us, as the next industrial revolution – it is a topic gathering considerably many more actors in academia as well as in the whole ecosystem of batteries.
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